The invention relates to a switching circuit consisting of CTD lines whose individual CTD lines have a unidirectional transmission behavior and whose recriprocal of characteristic impedance is determined by the size of their characteristic transfer capacitances.
Among other things, electric filter circuits have become known from the German Pat. No. 2,453,669 in whose construction self-contained loops with unidirectional transmission behavior can be used. Thereby, known CTD lines (charge transfer devices) can be considered as lines. Such lines are known per se as so-called bucket brigade devices or also as so-called CCD (charge coupled devices). For the operation of such circuit component parts, clock pulse generators are required, as this is likewise described in detail in the German Pat. No. 2,453,669. In this Letters Patent, among other things, it is already pointed out that bucket brigade devices which for example are described in the periodical "IEEE Solid State Circuits", Vol. SC4, June 1969, No. 3, Pages 131 through 136, can be advantageously employed as unidirectional transmission lines. In place of such bucket brigade devices, the aforementioned CCD lines can also be employed, i.e. transmission lines which work according to the principle of coupled charges. Such CCD lines, for example, are specified in "BSTJ" Vol. 49, Pages 589 through 593. The construction of filter circuits has likewise been already specified. As is known, it is often of particular significance precisely for the realization of filter circuits for attaining a predetermined transmission characteristic to provide attenuation peaks in the transmission characteristic upon real or complex frequencies, whereby steepness increases in the attenuation characteristic or the influencing of the transit time in the pass-band of the filter can be achieved. For the realization of such steepness-increased circuits, switching circuits are advantageous. Because of the unidirectional properties of the CTD lines employed here, however, switching circuits in the usual sense cannot be simulated here without further ado.